"It seems to be a general rule that a people which invaded a foreign country, to some degree adopted the pronunciation of its new home, partly as a result of the influence of climate, and partly also on account of the intermixture with the old inhabitants. This has also generally been supposed to have been the case in India. Thus there has been a long discussion as to whether the Aryans have adopted the cerebral letters from the Dravidas or have developed them independently. Good reasons have been adduced for both suppositions, and the question has not as yet been decided. The Indo-European languages do not seem to have possessed those letters. They had a series of dentals which were not, however, pronounced as pure dentals by putting the tongue between the teeth, but probably as alveolars, the tongue being pressed against the root of the upper teeth [as, for instance, in pronouncing the English -t- and -d-]. It is a well known fact that these sounds have in India partly become dentals and partly cerebrals. The cerebrals are in most cases derived from compound letters where the old dentals were preceded by an -l-. Similar changes also occur in other Indo-European languages, and it is therefore quite possible that the Indo-Aryan cerebrals have been developed quite independently. The cerebral letters, however, form an essential feature of the Dravidian phonology , and it therefore seems probable that Dravidian influence has been at work and at least given strength to a tendency which can, it is true , have taken its origin among the Aryans themselves."